Facile off-on fluorescence biosensing of human papillomavirus using DNA probe coupled with sunflower seed shells carbon dots

• A fluorescent biosensor for HPV16 detection based on off-on signal. • The quenching mechanism and fluorescence properties of SCDs were studied. • A strategy that requires no nucleic acid amplification and is highly sensitive. • Successful development and validation in spiked urine and cervical swabs sample. We report a fluorescent “off-on” platform based on carbon dots (CDs) and DNA probe to achieve trace detection of human papillomavirus 16 (HPV 16). Initially, the CDs was synthesized by simple two-step method, using biomass sunflower seed shells as precursor, doped with L-arginine and passivated by polyethyleneimine (PEI) to obtain positively charged biomass CDs that had the merits of high fluorescence intensity, green synthesis and good stability. Then, the DNA probe was prepared by modifying single-stranded DNA (ssDNA) with 4-(4-dimethylaminobenzazo) benzoyl (Dabcyl) fluorescence quenching agent. Due to electrostatic effect and Förster resonance energy transfer (FRET) mechanism, DNA probe can cause fluorescence quenching of the prepared CDs. Since HPV 16 bound to the DNA probe followed a strict base complementation pairing rule, it turned on the fluorescence of CDs by separating the DNA probe from the CDs. The limit of detection (LOD = 0.47 nM) and the linear range (0.5–150 nM) of the probe for HPV 16 were favorable. The recovery of HPV 16 in urine and cervical swabs were 96.6%-113.3% and 95.7%-103.9%. This method can achieve highly specific detection of the DNA sequences of target virus without complicated operation and expensive equipment, which is of great significance for biochemical analysis.